Representation of the ENSO Combination Mode and its Asymmetric SST Response in Different Resolutions of HadGEM3

Previous studies have revealed a combination mode （C-mode） occurring in the Indo-Pacific region, arising from nonlinear interactions between ENSO and the western Pacific warm pool annual cycle. This paper evaluates the simulation of this C-mode and its asymmetric SST response in HadGEM3 and its resolution sensitivity using three sets of simulations at horizontal resolutions of N96, N216 and N512. The results show that HadGEM3 can capture well the spatial pattern of the C-mode associated surface wind anomalies, as well as the asymmetric response of SST in the tropical Pacific, but it strongly overestimates the explained variability of the C-mode compared to the ENSO mode. The model with the three resolutions is able to reproduce the distinct spectral peaks of the C-mode at the near annual combination frequencies, but the performance in simulating the longer periods is not satisfactory, presumably due to the unrealistic simulation of the ENSO mode. Increasing the horizontal resolution can improve the consistency between atmospheric and oceanic representations of the C-mode, but not necessarily enhance the accuracy of C-mode simulation compared with observation.

Asymmetrical photonic spin Hall effect based on dielectric metasurfaces

The photonic spin Hall effect has attracted considerable research interest due to its potential applications in spincontrolled nanophotonic devices.However,realization of the asymmetrical photonic spin Hall effect with a single optical element is still a challenge due to the conjugation of the Pancharatnam-Berry phase,which reduces the flexibility in various applications.Here,we demonstrate an asymmetrical spin-dependent beam splitter based on a single-layer dielectric metasurface exhibiting strong and controllable optical response.The metasurface consists of an array of dielectric nanofins,where both varying rotation angles and feature sizes of the unit cells are utilized to create high-efficiency dielectric metasurfaces,which enables to break the conjugated characteristic of phase gradient.Thanks to the superiority of the phase modulation ability,when the fabricated metasurface is under normal incidence with a wavelength of 1550 nm,the lefthanded circular polarization(LCP)light exhibits an anomalous refraction angle of 28.9°,while the right-handed circular polarization(RCP)light transmits directly.The method we proposed can be used for the flexible manipulation of spin photons and has potentials in high efficiency metasurfaces with versatile functionalities,especially with metasurfaces in a compact space.

Growth asymmetry precedes differential auxin response during apical hook initiation in Arabidopsis

The development of a hook-like structure at the apical part of the soil-emerging organs has fascinated botanists for centuries,but how it is initiated remains unclear.Here,we demonstrate with highthroughput infrared imaging and 2-D clinostat treatment that,when gravity-induced root bending is absent,apical hook formation still takes place.In such scenarios,hook formation begins with a de novo growth asymmetry at the apical part of a straightly elongating hypocotyl.Remarkably,suchde novo asymmetric growth,but not the following hook enlargement,precedes the establishment of a detectable auxin response asymmetry,and is largely independent of auxin biosynthesis,transport and signaling.Moreover,we found that functional cortical microtubule array is essential for the following enlargement of hook curvature.When microtubule array was disrupted by oryzalin,the polar localization of PIN proteins and the formation of an auxin maximum became impaired at the to-be-hook region.Taken together,we propose a more comprehensive model for apical hook initiation,in which the microtubuledependent polar localization of PINs may mediate the instruction of growth asymmetry that is either stochastically taking place,induced by gravitropic response,or both,to generate a significant auxin gradient that drives the full development of the apical hook.

Modal parameter determination and chatter prediction for blade whirling: a comparative study based on symmetric and asymmetric FRF

Whirling has been adopted for the cost-effective machining of blade-shape components in addition to traditional end milling and flank milling processes.To satisfy the requirements of rotary forming in the blade whirling process,the workpiece must be clamped at both ends in suspension and rotated slowly during machining,which complicates the dynamics.This study aims to identify the dynamic characteristics within the blade whirling operation and present strategies for stability prediction.In this study,the dynamic characteristics of a whirling system are modeled by assuming symmetric and asymmetric parameters.Theoretical prediction frequency response function(FRF)results are compared with experimental results.Moreover,semi-discretization stability lobe diagrams(SLDs)obtained using the dynamic parameters of these models are investigated experimentally.The results show that the asymmetric model is more suitable for describing the whirling system,whereas the symmetric model presents limitations associated with the frequency range and location of measuring points.Finally,a set of airfoil propeller blade whirling operations is conducted to verify the prediction accuracy.